Hydraulic fracturing has gained increased popularity in the oil and gas industry in the last few years. According to one survey, hydraulic fracturing has been used in nine out of ten natural gas wells in the United States.
In a typical hydraulic fracturing process, a well is drilled and a casing pipe is inserted into the well which has been perforated in specific target zones. A solution containing various chemicals is then introduced into the target zones under high-pressure and/or temperature resulting in the formation to crack/fracture, thereby releasing natural gases/hydrocarbons which can then be drawn via the pipe to the surface.
Because large amounts of water, sand and chemicals are pumped underground to break apart the rock and release the gas, serious concerns have been raised that some of these chemicals may contaminate water supplies. For instance, fracture treatments in coal bed methane wells may use 50,000 to 350,000 gallons of water per well, while deeper shale wells can use 2-10 million gallons of water to fracture just a single well. The contamination may occur directly when the fracking fluid gets in contact with clean water supply or it may happen indirectly through waste disposal practice.
In addition to the large amount of water used, a number of chemicals are simultaneously injected into the process in an effort to dissolve and/or loosen organic and inorganic materials, which may help freeing up more pathways for the gas to flow.
In a typical fracking fluid, there are a number of additives which may include buffering agents, acids and/or bases, corrosion inhibitors, and organic solvents (e.g., aromatics). Such components may include, for example, proppants, acids, biocides, heavy aromatic naphtha, hydrochloric acid, sodium hydroxide, sodium hypochlorite, trimethyl benzene, naphthalene, and polyacrylates.
Many of these chemicals are excellent at breaking high MW hydrocarbon emulsions which may inhibit the flow of gases in the well. However, many of these chemicals are known toxins and have high flammability. Examples of such chemicals include dichloroethane, light distallates, benzene, toluene, ethylene glycol, butoxyethanol, naphthalene, and ethylbenzene. If these chemicals find their way to groundwater/water tables, they may pose immediate threats to drinking water for humans and animals.
Many fracking sites contain naturally occurring tectonic conduits which provide a transportation route for the injected fluids back to the surface. These re-emerged liquids may compromise the purity of groundwater/drinking water supplies.
According to a recent EPA study, cancerous compounds have been found in the vicinity of a fracking site in Wyoming. Accordingly to the report, butoxyethanol and other solvents such as acetone, toluene, naphthalene and diesel fuel were found in the local water supplies. These toxic chemicals have been associated with the local fracking operations.
In light of the potential danger posed by these chemicals, some have recommended that all fracking fluid chemicals be disposed of at hazardous waste sites. However, such disposal practice can be extremely costly.